The structure of photosystem I from a high-light-tolerant cyanobacteria

eLife

Michael Reppert¹  Safa Ahad¹  Dewight Williams²  Hila Toporik³  Natalie Vaughn³  Jackson Vanlandingham³  Zachary Dobson³  Yuval Mazor³  Petra Fromme³  Michael Vaughn³ 

[1] Department of Chemistry, Purdue University, West Lafayette, United States;John M. Cowley Center for High Resolution Electron Microscopy, Arizona State University, Tempe, United States;School of Molecular Sciences, Arizona State University, Tempe, United States;BiodesignCenter for Applied Structural Discovery, Arizona State University, Tempe, United States;

关键词: cyanobacterium aponinum;    cyanobacteria;    extermophile;    photosynthesis;    light reactions;    photosystems;    Other;   

DOI  :  10.7554/eLife.67518

来源: eLife Sciences Publications, Ltd

【 摘 要 】

Photosynthetic organisms have adapted to survive a myriad of extreme environments from the earth’s deserts to its poles, yet the proteins that carry out the light reactions of photosynthesis are highly conserved from the cyanobacteria to modern day crops. To investigate adaptations of the photosynthetic machinery in cyanobacteria to excessive light stress, we isolated a new strain of cyanobacteria, Cyanobacterium aponinum 0216, from the extreme light environment of the Sonoran Desert. Here we report the biochemical characterization and the 2.7 Å resolution structure of trimeric photosystem I from this high-light-tolerant cyanobacterium. The structure shows a new conformation of the PsaL C-terminus that supports trimer formation of cyanobacterial photosystem I. The spectroscopic analysis of this photosystem I revealed a decrease in far-red absorption, which is attributed to a decrease in the number of long- wavelength chlorophylls. Using these findings, we constructed two chimeric PSIs in Synechocystis sp. PCC 6803 demonstrating how unique structural features in photosynthetic complexes can change spectroscopic properties, allowing organisms to thrive under different environmental stresses.

【 授权许可】

CC BY